/*

https://leetcode.com/problems/two-sum/

​

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

​

You may assume that each input would have exactly one solution, and you may not use the same element twice.

​

Example:

​

Given nums = [2, 7, 11, 15], target = 9,

​

Because nums[0] + nums[1] = 2 + 7 = 9,

return [0, 1].

*/

​

using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        int x = 7;//int.Parse(Console.ReadLine());

        int[] result = TwoSum_On2(new int[]{1,2,3,4,5,6}, x);

        Console.WriteLine(result[0].ToString() + ", " + result[1].ToString());

    }

    public static int[] TwoSum_On(int[] nums, int target) {

        Dictionary<int, int> tries = new Dictionary<int, int>();

        int rest;

        for(var i = 0; i < nums.Length; i++){

            rest = target - nums[i];

            if(tries.ContainsKey(rest)) return new int[]{tries[rest], i};

​

            tries.Add(nums[i], i);      

        }

        return new int[] {0,0};

​

    }

    public static int[] TwoSum_On2(int[] nums, int target) {

        int[] result = new int[2];

        for(var i = 0; i< nums.Length;i++){

            target -= nums[i];

            result[0]=i;

            for(var j = 0; j< nums.Length; j++){

                target -= nums[j];

                result[1] = j;

                if(target == 0) return result;

                target += nums[j];

            }

            target += nums[i];          

        }

        return new int[] {0,0};

​

    }

}